A student simplified the expression 5x — 3(x + 4) to 2x + 12. Find the student's error and correct it.

The first thing I would do, to make it easier for yourself, is change the equation to:

5x + -3(x + -4)

or 5x plus -3(x plus -4)

Then you need to "distribute" -3 to both parts inside the parentheses (x+ -4).  The first part, 5x, won't change at all.

5x plus -3 times (the rest.)  Multiply -3 times each part inside the parentheses now.

5x + (-3)(x) +(-3)(-4)

5x + -3x + -12

5x-3x +-12

2x  + -12

2x-12

step-by-step explanation:

yes

yes yes yes